1. Field of the Invention
The invention relates to optical communications devices, such as transmitters, receivers, and transceivers used in high throughput fiber optic communications links in local and wide area networks and storage networks and in particular to parametric monitoring of the performance of such devices in the host system or by a system manager.
2. Description of the Related Art
Communications networks have experienced dramatic growth in data transmission traffic in recent years due to worldwide Internet access, e-mail, and e-commerce. As Internet usage grows to include transmission of larger data files, including content such as full motion video on-demand (including HDTV), multi-channel high quality audio, online video conferencing, image transfer, and other broadband applications, the delivery of such data will place a greater demand on available bandwidth. The bulk of this traffic is already routed through the optical networking infrastructure used by local and long distance carriers, as well as Internet service providers. Since optical fiber offers substantially greater bandwidth capacity, is less error prone, and is easier to administer than conventional copper wire technologies, it is not surprising to see increased deployment of optical fiber in data centers, storage area networks, and enterprise computer networks for short range network unit to network unit interconnection.
Such increased deployment has created a demand for electrical and optical transceiver modules that enable data system units such as computers, storage units, routers, and similar devices to be optionally coupled by either an electrical cable or an optical fiber to provide a high speed, short reach (less than 50 meters) data link within the data center.
A variety of optical transceiver modules are known in the art to provide such interconnection that include an optical transmit portion that converts an electrical signal into a modulated light beam that is coupled to a first optical fiber, and a receive portion that receives a second optical signal from a second optical fiber and converts it into an electrical signal, and similar implementations employ one fiber for both optical signals, traveling in opposite directions. The electrical signals are transferred in both directions over an electrical connectors that interface with the network unit using a standard electrical data link protocol.
The optical transmitter section includes one or more semiconductor lasers and an optical assembly to focus or direct the light from the lasers into an optical fiber, which in turn, is connected to a receptacle or connector on the transceiver to allow an external optical fiber to be connected thereto using a standard connector, such as SC, FC or LC. The semiconductor lasers are typically packaged in a hermetically sealed can or similar housing in order to protect the laser from humidity or other harsh environmental conditions. The semiconductor laser chip is typically a distributed feedback (DFB) laser with dimensions a few hundred microns to a couple of millimeters wide and 100-500 microns thick. The package in which they are mounted typically includes a heat sink or spreader, and has several electrical leads coming out of the package to provide power and signal inputs to the laser chips. The electrical leads are then soldered to the circuit board in the optical transceiver. The optical receive section includes an optical assembly to focus or direct the light from the optical fiber onto a photodetector, which in turn, is connected to a transimpedance amplifier/limiter circuit on a circuit board. The photodetector or photodiode it typically packaged in a hermetically sealed package in order to protect it from harsh environmental conditions. The photodiodes are semiconductor chips that are typically a few hundred microns to a couple of millimeters wide and 100-500 microns thick. The package in which they are mounted is typically from three to six millimeters in diameter, and two to five millimeters tall and has several electrical leads coming out of the package. These electrical leads are then soldered to the circuit board containing the amplifier/limiter and other circuits for processing the electrical signal.
Optical transceiver modules are therefore packaged in a number of standard form factors which are “hot pluggable” into a rack mounted line card network unit or the chassis of the data system unit. Standard form factors set forth in Multiple Source Agreements (MSAs) provide standardized dimensions and input/output interfaces that allow devices from different manufacturers to be used interchangeably. Some of the most popular MSAs include XENPAK (see www.xenpak.org), X2 (see www.X2msa.org), SFF (“small form factor”), SFP (“small form factor pluggable”), XFP (“10 Gigabit Small Form Factor Pluggable”, see www.XFPMSA.org), and the 300-pin module (see www.300pinmsa.org).
Customers and users of such modules are interested in small or miniaturized transceivers in order to increase the number of interconnections or port density associated with the network unit, such as, for example in rack mounted line cards, switch boxes, cabling patch panels, wiring closets, and computer I/O interfaces.
The identification of individual modules in connection with assessing reliability of such modules is an important consideration network management. When a module degrades or fails, users must reconfigure the system to bypass the inoperative module. Moreover, performance degradation must be understood as an essential step in preventing recurrence of that failure. Thus, producers of optical modules expend much effort in failure analysis to determine the root cause of any failures that occur and to subsequently improve products to eliminate similar failures in the future. Such failure analysis is after the fact, and very labor intensive, requiring technologists referred to as reliability analysts. Such failure analysis often requires an extensive suite of test equipment, which also represents a significant expense to the manufacturer.
The failure analysis process is relatively expensive to the manufacturer, and consequently the producer has an interest in conducting the analysis as efficiently as possible such as when the module is still installed in the system. Additionally, sometimes the failure is covered by a warranty, and honoring the warranty represents an expense to the manufacturer.
If more information regarding the operational history of the optical module could be made available during a real time basis, then determining the warranty status would be made more straightforward, and aspects of the failure analysis would be simpler. Failure analysis involves a search for information about the causes and circumstances of product failure, often by exploiting very subtle clues, and any information that can be made explicitly available to the reliability analyst has the potential to make their task more productive, effective, and efficient.
This concept of module data analysis is extendable to cases in which no failure has occurred. In this case, a reliability analyst may analyze a used optical module to observe parametric shifts in performance, and the information gained may be used to define design and manufacturing process improvements to make the product even more reliable in the future. Because of the importance of reducing failures and parametric shifts in product performance, a need exists for better methods of tracking operational performance of optical modules by a network management system.
Various techniques to control access to a network by a terminal or user are well known in the prior art, the simplest of which include passwords, serial numbers or use IDs, PIN codes, and dedicated hardware with cryptographic keys. Such prior art is usually directed to preventing network access by an unauthorized user. In the context of the present invention, the concern which has led to the present invention is not an unauthorized user but an unauthorized or counterfeit module. Stated another way, in a commercial environment in which network units or components such as optoelectronic modules or transceivers are standardized in form, fit, and function, it is useful for the host equipment vendor or network manager to have a mechanism to ensure that only network units or components from certain approved suppliers, or having certain predefined operational, reliability, or quality of service characteristics, are only utilized in the network, and that “generic” units, or units not meeting certain operational characteristics are electronically rejected and denied access or use in the network.
Identification information, such as transceiver type, capability, serial number, compatibility information may be stored, or be capable of being stored, in a transceiver (see, for example, U.S. Patent Application Publication 2003/0128411). Prior to the present invention such information has not been utilized in the context of authorizing use of a particular module in a host unit or network into which it has been plugged, or for monitoring or assessing reliability of such modules during real time operation.
Prior to the present invention, it had not been possible for a data communications network to detect the presence of unauthorized network units or a component's capability or access to such network.